Use of varying constraints in optimal 3-D graph search for segmentation of macular optical coherence tomography images.

An optimal 3-D graph search approach designed for simultaneous multiple surface detection is extended to allow for varying smoothness and surface interaction constraints instead of the traditionally used constant constraints. We apply the method to the intraretinal layer segmentation of 24 3-D optical coherence tomography (OCT) images, learning the constraints from examples in a leave-one-subject-out fashion. Introducing the varying constraints decreased the mean unsigned border positioning errors (mean error of 7.3 +/- 3.7 microm using varying constraints compared to 8.3 +/- 4.9 microm using constant constraints and 8.2 +/- 3.5 microm for the inter-observer variability).